Herpes Virus Kills Cancer in Possible Medical Breakthrough

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Microscope view of a virus known as SV40.Credit: Wikimedia Commons

A genetically modified strain of herpes, a virus that typically causes blisters around the mouth or in the genitals, can kill cancer cells and stop tumors from growing, according to new research.

The research, published in the Journal of Clinical Oncology on Wednesday, is the first positive, late-phase trial result for cancer “virotherapy,” the use of a virus to kill cancer cells.

If approved, the drug used in the research could be widely available for cancer patients by next year, scientists predicted.

Unlike chemotherapy, which casts a wide net and kills all proliferating cells, viruses can be targeted against cancer cells, which could make them more effective in fighting the disease.

The method also appeals to researchers because it activates the immune system to fight cancer.

Crucially, the therapy has the potential to overcome cancer even when the disease has spread to organs throughout the body, offering hope in future to patients who have been faced with the bleakest prognosis.

The trial involved more than 400 patients with aggressive melanoma, a skin cancer. One in four patients responded to the treatment, and 16% were still in remission after six months. About 10% of the patients treated had “complete remission,” with no detectable cancer.

Importantly, all the patients had inoperable, relapsed or metastatic melanoma with no conventional treatment options available to them.

The herpes multiplies vigorously inside the cancer cells until they burst open, spilling the virus into the surrounding area, triggering a secondary immune reaction against the tumor.

“It’s like an unmasking of the cancer,” said Kevin Harrington, professor of biological cancer therapies at the Institute of Cancer Research London, who led the work.

“The patient’s immune system wakes up and attacks the cancer cells wherever they are in the body.”

Once the immune system has been nudged into action by the treatment, it appears to develop an enhanced ability to detect and attack cancer throughout the body. Scientists are not sure why this happens, but the latest trial confirmed the effect, showing that even secondary tumors that had not been infected by the virus shrank or disappeared.

The drug, called T-VEC, has been submitted to both the FDA and the European Medicines Agency. If approved, it could be available to U.S. patients by next year and in Europe soon afterwards. Similar treatments for head and neck cancers are in trial.

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